The structures and properties of FeSin/FeSi/FeSi (n = 1 ~ 8) clusters
School of Chemistry and Environment, South China Normal
510006, Guangdong, P.R.
Received in final form: 14 March 2011
Published online: 27 July 2011
The geometry, stability, and electronic properties of iron-doped silicon clusters FeSin/FeSi/FeSi (n = 1 ~ 8) have been systematically investigated using the density functional theory (DFT) approach at the B3LYP/6-311+G* level. Our results show that the ground state structures of FeSin/FeSi/FeSi change from planar to three-dimensional for n > 3. Bipyramidal structures, or their face-capped isomers, are favored for the larger clusters. For neutral FeSin clusters, their ground state structures are the trigonal, tetragonal, capped tetragonal, capped pentagonal, and combined tetragonal bipyramids for n = 4 ~ 8, respectively. The lowest-energy structures of the anionic FeSi clusters essentially retain similar frameworks to their neutral counterparts, while those of the cationic FeSi clusters are significantly deformed; this is confirmed by their calculated ionization potential and electronic affinity values. For most of the stable structures, the spin electronic configurations are s = 1 or 2 for neutral FeSin, s = 3/2 or 5/2 for ionic FeSi/FeSi. The average binding energy values generally increase with increasing cluster size, indicating the clusters can continue to gain energy during the growth process. Fragmentation and second-order energy peaks (maxima) are found at n = 2, 5, and 7 for FeSin/FeSi, n = 4 and 6 for FeSi, suggesting that these clusters possess higher relative stability. Furthermore, the HOMO-LUMO gap values show that anionic FeSi have greater chemical reactivity than cationic FeSi and neutral FeSin, except when n = 7.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2011